The use of name-variant partial for filtering is an exhaustive attempt to retrieve as many relevant documents as possible at the cost of retrieving irrelevant documents. However, we still miss about  2363(10\%) of the vital-relevant documents.  Why are these documents missed? If they are not mentioned by partial names of name variants, what are they mentioned by? Table \ref{tab:miss} shows the documents that we miss with respect to cleansed and raw corpus.  The upper part shows the number of documents missing from cleansed and raw versions of the corpus. The lower part of the table shows the intersections and exclusions in each corpus.  

In this paper, we examined the filtering stage of the entity-centric

stream filtering and ranking  by holding the later stages of fixed. In

particular, we studied the cleansing step, different techniques to

construct entity profiles, and the effects of entity type (Wikipedia

or Twitter) and document category (news, social, or other). We attempted to address

the following research questions: 1) does cleansing affect filtering

and subsequent performance? 2) what is the most effective way of

entity profiling? 3) is filtering different for Wikipedia and Twitter

entities? 4) are some type of documents easily filterable and others

not? 5) does a gain in recall at filtering step translate to a gain in

max-F at the end of the pipeline? and 6) what are the

circumstances under which vital documents can not be retrieved?

Cleansing may remove (parts of) the contents of documents, making

them irretrievable. However, because of the introduction of false

positives, gaining recall by filtering the raw corpus instead of the

cleansed one and developing richer entity profiles, does not necessarily translate to overall

performance gains. The overall conclusion on this is mixed in the

sense that cleansing has helped to improve the recall on vital

documents and Wikipedia entities, but at the same time reduces the

recall on Twitter entities and the relative category of 

relevance ranking. Vital and relevant documents show a difference in

retrieval performance, where vital documents appear to be easier to filter than

relevant ones. Notice that in the context of the CCR task, the vital documents are

most important. 

Despite an exhaustive attempt to identify as many vital-relevant

documents as possible,  we observe that there are still documents that

we miss. While some can clearly be retrieved by modifying the

filtering procedure, some relevant and even vital documents can be

considered irretrievable. The circumstances under

which this happens are many. A few documents have no content, or it is

unclear why they have been judged vital. However, the main

circumstances under which vital documents 

can defy filtering include: outgoing link mentions,

venue-event, entity - related entity, organization - main area of

operation, entity - group, artist - artist's work,  party-politician,

and world knowledge.